I've always had a slight hitch in my reading of Luke 15:7:
I tell you, in just the same way there will be more joy in heaven over one sinner who repents than over ninety-nine righteous people who have no need of repentance.
I get the irony here, that there aren't any righteous people who have no need of repentance*, but it still seems a bit... insulting? patronizing? toward the righteous. (Not quite entirely unlike the way characters who are good from start to finish come off as less interesting in stories than characters who are bad.)
"Two people were in debt to a certain creditor; one owed five hundred days' wages and the other owed fifty. Since they were unable to repay the debt, he forgave it for both. Which of them will love him more?"
Simon said in reply, "The one, I suppose, whose larger debt was forgiven."
He said to him, "You have judged rightly."
The greater joy, then, need not rest in the more interesting personal history. It may be founded upon the greater love of the one whose larger debt was forgiven.
Which of course pops us back to Luke 15 and the Prodigal Son, in which the righteous one who has no need of repentance not only loves his father less, but is actively nursing a grudge against him.
* The Catena Aurea includes this quotation, attributed to Bede, though found in Anselm and possibly derived from Augustine: "The Lord found the sheep when He restored man, and over that sheep that is found there is more joy in heaven than over the ninety and nine, because there is a greater matter for thanksgiving to God in the restoration of man than in the creation of the Angels. Wonderfully are the Angels made, but more wonderfully man restored." The Angels, I suppose, are cool with that.